Most bacteria, including oral streptococci, utilize a phosphoenolpyruvate (PEP) driven active transport system for the uptake of hexoses and hexitols as well as some higher sugars. The phosphorylated products of this system enter directly into metabolic pathways. This study has established the presence of a highly specific glucokinase and fructokinase (fructokinase has activity toward mannose as well) which provide an altervative pathway for permeation and phosphorylation of carbohydrates. The glucokinase has been purified to homogeneity and its properties characterized. Current work is directed at elucidating the mechanism of regulation of glucokinase synthesis. Factors such as growth carbohydrate and pH control intracellular specific activity levels. Understanding the interrelationship the role of these two distinct pathways of carbohydrate uptake is the ultimate object of the project. BIBLIOGRAPHIC REFERENCES: Chassy, B.M., Beall, R.M., Jr., Belawski, R.M., Porter, E.V. and Donkersloot, J.A.: Occurance and distribution of sucrose metabolizing enzymes in oral streptococci. Infection and Immunity 14: 408-415, 1976. Donkersloot, J.A., deLeon, H.A., Chassy, B.M. and Krichevsky, M.I.: Analysis of the exudate produced by Streptococcus mutans SL-1 colonies on sucrose-containing agar media. Applied Environmental Microbiology 32: 448-450, 1976.